The signalling system has gone into different methods to the challenges of the technology and in the process evolves from the olden days of Lower Quadrant signalling system to Upper Quadrant signal, Multi Aspect Color Light signalling to MACLS with Panel Interlocking, Route Relay Interlocking, Audio Frequency Track Circuit signalling system, Optic fiber cable laying with Quad cable and Block Proving Axel Counters, Intermediate block signalling and reaches to the electronic interlocking system.

The scope of work involves in all the above cases is designing, supplies, laying of signalling/Power/quad cables, erection of apparatus cases and color light signals, provision of track circuits, wiring of plug-in type relays at relay room and apparatus cases, termination in apparatus cases and cable termination rack, wiring of relays and provision of interconnections, supply and installation of signal equipments, supply and installation, testing and commissioning.